Published research (Pinnell et al., Dermatologic Surgery, 2001) found that percutaneous absorption of L-Ascorbic Acid plateaus around 20%. Higher percentages can cause irritation without increasing benefits, while lower percentages may be less effective on stubborn hyperpigmentation.

Derivatives (like Sodium Ascorbyl Phosphate) must be converted by the skin into L-Ascorbic Acid, losing potency in the process. MD® uses Pure L-Ascorbic Acid for immediate, non-converted antioxidant action.

USP-grade means the raw ingredient meets the purity and identity specifications set by the United States Pharmacopeia.

Our serum is formulated at an acidic pH of approximately 2.7, which is essential for pure Vitamin C to be absorbed effectively by the skin.

Water-based formulas have higher molecular mobility. This allows the 20% concentration to absorb quickly without the "greasy" film or "metallic" smell typical of oil-stabilized serums.

Colour is a useful indicator: a clear-to-pale serum is still active, while a dark amber colour indicates oxidation. Our stabilisation system is designed to keep the formula clear for up to 12 months when stored correctly.

Thanks to our stabilisation system, the serum remains active for 12 months after opening when stored in a cool, dark place.

While not required, refrigeration can extend shelf life and provides a cooling effect that helps de-puff skin during morning application.

That smell usually comes from ferulic acid or the oils used to stabilise some Vitamin C formulas. Because ours uses a high-purity water base without those ingredients, it is virtually odourless and fragrance-free.

A pale champagne tint is fine, but a dark amber color means the Vitamin C has oxidized. Our formula is engineered for stability and is designed to resist this colour change through its 12-month shelf life.

For best results, follow a circadian rhythm approach: use Vitamin C in the morning for environmental defense and Retinol in the evening for cellular repair. Applying them together in the same window can cause pH conflicts that may neutralize the effectiveness of both active ingredients.

A 10-minute wait is recommended to allow the skin’s pH to adjust and for the 20% L-Ascorbic Acid to be fully absorbed. This helps the high-concentration treatment settle in before other products potentially neutralize the acidic environment it requires to work.

Because of the potent 20% concentration, 3–5 drops are sufficient to cover the entire face, neck, and décolletage. The water-based formula provides high molecular mobility, so a small amount spreads easily and absorbs quickly.

Apply MD® Vitamin C to clean, dry skin. Excess water on the skin's surface can raise the pH level, which may dilute the specific acidic environment required for the L-Ascorbic Acid to be absorbed effectively.

You can apply the serum along the orbital bone (the firm area under the eye) to target the appearance of fine lines and crow’s feet. However, avoid the immediate lash line and eyelids, as the 20% concentration is highly potent for those specific thin-skin areas.

L-Ascorbic Acid inhibits tyrosinase, the enzyme involved in melanin production, which is why Vitamin C is widely used to help improve the appearance of dark spots and uneven tone. Melasma is a medical condition and should be managed with your dermatologist.

Vitamin C is a cofactor in collagen synthesis, and with consistent use skin can look firmer, with pores appearing less noticeable.

High-Energy Visible (HEV) blue light from digital screens generates oxidative stress. Antioxidants such as Vitamin C help neutralise free radicals generated by environmental exposure, including HEV light from screens.

Unlike many luxury serums that use heavy oils for stability, our formula features an oil-free water base that was assessed as non-comedogenic under test conditions. This allows high-potency antioxidant delivery without a greasy residue, making it well suited to oily and blemish-prone complexions.

The skin on the neck and chest is thinner and more prone to "creping" and sun damage. Applying the serum to the neck and chest helps improve the look of tone and texture in areas that show sun damage and creping earlier than the face.

A brief tingling can occur with a low-pH formula. It usually settles within a few minutes as skin adjusts. If it does not settle, or if you experience burning or persistent redness, rinse off and discontinue use.

Vitamin C does not typically cause breakouts. If you notice new congestion after starting the serum, reduce frequency, and if it persists, discontinue use and consult a dermatologist.

Mild tingling on first use is common. If redness or irritation persists, discontinue use — this may indicate a sensitivity. If you would prefer to try a gentler introduction first, reduce to every other day or dilute a few drops into your moisturiser.

No, Vitamin C does not make skin more sun-sensitive. It is an antioxidant, not a sunscreen, and offers no SPF — always pair it with a broad-spectrum SPF 30+.

Smoking significantly depletes Vitamin C levels in the skin, leading to a sallow or dull appearance. Topical Vitamin C can help restore radiance to skin that looks dull or sallow from oxidative stress.